2004–2006 Puget Sound Traffic Choices Study

The 2004–2006 Puget Sound Traffic Choices Study tested the hypothesis that time-of-day variable road tolling in Seattle, Washington, could reduce traffic congestion and generate revenue.

Data Collection Agency

In 2002, the Puget Sound Regional Council (PSRC) received a grant from the Federal Highway Administration for a pilot project on congestion-based tolling.


To test the hypothesis, the study placed global positioning system (GPS) data loggers into the vehicles of about 275 households in the Seattle metropolitan area. The project recorded roughly 18 months of trip data (from November 2004 to April 2006) and included more than 400 vehicles. For most vehicles, the tolling influence experiment phase of the study began in July 2005 and lasted for 32 weeks. The three months immediately preceding the experiment period for each vehicle served as the control period.

To implement the hypothetical tolling schedule, drivers were given individual endowment accounts against which tolls were charged based on their use of the road network. The initial amount placed in the endowment accounts was calculated such that a zero balance would remain at the end of the experiment period if drivers did not change their travel behavior. If drivers did change their behavior, they got to keep any positive balance remaining in the endowment account at the end of the study. Participants did not spend any of their own money on the toll charges, even if they fully depleted their endowment accounts.

Survey Records

Survey records include 434 participants.

More Information

For an overview and evaluation of the traffic choices study, see the Traffic Choices Study Summary Report.

Transportation Data

The PSRC data set contains data from 329 unique households and 484 vehicles. By the study's conclusion, the toll system had issued more than 4,000 billing invoices, recorded more than 750,000 individual vehicle trip records, and logged more than 4.5 million vehicle miles travelled. For details on available data and variable definitions, see the data dictionary.

Transportation data are available as zipped files. Download Winzip.

Full Survey Data

(excluding any GPS)


Data Sorted by Vehicle

(with unfiltered GPS speed, if included)


For the study's latitude and longitude data, learn how to access the spatial data.

How to Cite the Data

If you use TSDC data in a publication, please contact us and include a citation in your publication consistent with the following format:

"Transportation Secure Data Center." (2017). National Renewable Energy Laboratory. Accessed Jan. 15, 2017: www.nrel.gov/tsdc.